WASHINGTON (CNN) -- Attorney General Eric Holder said Wednesday that he would "follow the law" as he weighed potential prosecutions of Bush administration officials who authorized controversial harsh interrogation techniques.

Some groups want Attorney General Eric Holder to appoint a special prosecutor to investigate the issue.

In Holder's first public comments on the issue since President Obama's statements on the matter Tuesday, the attorney general responded to questions briefly and cautiously.

"We are going to follow the evidence, follow the law and take that where it leads. No one is above the law," Holder said at an Earth Day event.

Some human rights groups have demanded that Holder appoint a special prosecutor to investigate the matter, but the attorney general appears to be in no hurry to decide how to proceed.

Obama said Tuesday that the attorney general would ultimately decide whether to proceed with prosecutions of those in the Bush administration who drew up the legal basis for aggressive interrogation techniques.

Those techniques include waterboarding, which simulates drowning. Obama has called the practice torture. Other techniques include keeping the prisoner in "stress positions" for long periods of time, enclosing the prisoner's head in a box with insects he is told are poisonous, and sleep deprivation.

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The administration last week released four lengthy, Bush-era legal memorandums -- one from 2002 and three from 2005 -- that concluded the harsh interrogation techniques did not constitute torture and were not against the law.

Holder also repeated assurances the Obama administration had given CIA interrogators who employed the controversial techniques that they would not be charged.

"The president's comments were consistent with what we've said all along. Those who, in good faith, followed legal guidance they were given will not be prosecuted or investigated," Holder said.

Sen. Jay Rockefeller, who earlier in the day released a newly declassified timeline -- compiled when he was chairman of the Senate Intelligence Committee -- of how the approval for the controversial interrogation techniques played out, said he agreed that CIA operatives shouldn't face prosecution.

"But I am not prepared to say the same for the senior Bush administration officials who authorized or directed these policies in the first place," the West Virginia Democrat said. "The focus for right now should be on finding the facts."

Several investigations, both internal and external, are under way into the interrogation or related matters, and others are almost certain to be launched, particularly by Congress

The attorney general's comments came at a public park in Washington where he helped plant a tree to mark the environmental celebration of Earth Day.